[v3,2/8] idmapped-mounts: switch to getopt_long_only()

Commit Message

Christian Brauner Aug. 12, 2021, 4:01 p.m. UTC

From: Christian Brauner <[e-mail]>

We're not using the shortopts anywhere anyway so just rely on longopts.

Cc: [e-mail]
Suggested-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>
---
/* v2 */
patch not present

/* v3 */
- Christoph Hellwig <[e-mail]>:
  - Split into separate patch.
---
 src/idmapped-mounts/idmapped-mounts.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Comments

Christoph Hellwig Aug. 14, 2021, 8:42 a.m. UTC | #1

> -	while ((ret = getopt_long(argc, argv, "", longopts, &index)) != -1) {
> +	while ((ret = getopt_long_only(argc, argv, "d:f:m:sh", longopts, &index)) != -1) {

Hmm.  From the manpage:

"(If the program accepts only long options, then optstring should be specified
as an  empty  string (""),  not  NULL.)"

So I think the empty opstring should remain.

Also later in the man page:

" getopt_long_only() is like getopt_long(), but '-' as well as "--" can
indicate a long option."

So maybe my advise to switch to getopt_long_only wasn't needed or is
even not that helpful.  Sorry, it's been a while since I wrote programs
with non-trivial option parsing.

Christian Brauner Aug. 14, 2021, 10:13 a.m. UTC | #2

On Sat, Aug 14, 2021 at 10:42:34AM +0200, Christoph Hellwig wrote:
> > -	while ((ret = getopt_long(argc, argv, "", longopts, &index)) != -1) {
> > +	while ((ret = getopt_long_only(argc, argv, "d:f:m:sh", longopts, &index)) != -1) {
> 
> Hmm.  From the manpage:
> 
> "(If the program accepts only long options, then optstring should be specified
> as an  empty  string (""),  not  NULL.)"
> 
> So I think the empty opstring should remain.
> 
> Also later in the man page:
> 
> " getopt_long_only() is like getopt_long(), but '-' as well as "--" can
> indicate a long option."
> 
> So maybe my advise to switch to getopt_long_only wasn't needed or is
> even not that helpful.  Sorry, it's been a while since I wrote programs
> with non-trivial option parsing.

Nah, that's perfectly fine. I think the getopt_long_only() switch was
good. We don't anywhere use and shouldn't encourage using shortopts.
It's much more descriptive to see

$here/src/idmapped-mounts/idmapped-mounts \
	--test-btrfs \
	--device "$TEST_DEV" \
	--mountpoint "$TEST_DIR" \
	--scratch-device "$SCRATCH_DEV" \
	--scratch-mountpoint "$SCRATCH_MNT"
	--fstype "$FSTYP"

than it is to see e.g.:

$here/src/idmapped-mounts/idmapped-mounts \
	-b 
	-d "$TEST_DEV" \
	-m "$TEST_DIR" \
	-s "$SCRATCH_DEV" \
	-a "$SCRATCH_MNT" \
	-f "$FSTYP"

In the second case I have to go check the source code to make sure that
this is the correct option. In the first case I can just read it in the
test itself. So I think we'll keep it but I'll remove the option string
like you pointed out.

Christian

Patch

diff --git a/src/idmapped-mounts/idmapped-mounts.c b/src/idmapped-mounts/idmapped-mounts.c
index 69dcc027..e565246e 100644
--- a/src/idmapped-mounts/idmapped-mounts.c
+++ b/src/idmapped-mounts/idmapped-mounts.c
@@ -8717,8 +8717,11 @@  static void usage(void)
 	fprintf(stderr, "    Run idmapped mount tests\n\n");
 
 	fprintf(stderr, "Arguments:\n");
-	fprintf(stderr, "-d --device        Device used in the tests\n");
-	fprintf(stderr, "-m --mountpoint    Mountpoint of device\n");
+	fprintf(stderr, "--device        Device used in the tests\n");
+	fprintf(stderr, "--fstype        Filesystem type used in the tests\n");
+	fprintf(stderr, "--help          Print help\n");
+	fprintf(stderr, "--mountpoint    Mountpoint of device\n");
+	fprintf(stderr, "--supported     Test whether idmapped mounts are supported on this filesystem\n");
 
 	_exit(EXIT_SUCCESS);
 }
@@ -8826,7 +8829,7 @@  int main(int argc, char *argv[])
 	int index = 0;
 	bool supported = false;
 
-	while ((ret = getopt_long(argc, argv, "", longopts, &index)) != -1) {
+	while ((ret = getopt_long_only(argc, argv, "d:f:m:sh", longopts, &index)) != -1) {
 		switch (ret) {
 		case 'd':
 			t_device = optarg;